Hydrostor

Hydrostor was founded in 2010 in Toronto, Canada by Curtis VanWalleghem (CEO) and Cameron Lewis. VanWalleghem, who left a career at nuclear generator Bruce Power and Deloitte's corporate strategy practice to pursue the opportunity, met Lewis at Bruce Power, where Lewis held two patents for an improved approach to compressed air energy storage. Their key innovation: rather than using natural caverns at specific geographic locations (the approach of the world's two existing compressed air storage facilities in Alabama and Germany), Hydrostor mines hard-rock caverns 600 metres underground at nearly any location with suitable bedrock. Air is compressed into the cavern at the same pressure as the surrounding groundwater, which provides a constant, water-weighted back-pressure that makes the system work without the natural-gas heating step required by conventional CAES. The result is a zero-emissions, long-duration storage system deployable close to urban load centers, transmission substations, and renewable energy generation.

Hydrostor was founded on the conviction that wind and solar are the cheapest forms of energy ever produced, but that grids relying heavily on them need 8+ hours of storage to remain reliable when the sun sets and winds calm. Existing lithium-ion batteries are too expensive for durations beyond four hours. Pumped hydroelectric — the world's dominant long-duration storage technology — requires specific mountain topography, limiting it to a small number of sites globally. Hydrostor's Advanced Compressed Air Energy Storage (A-CAES) can be sited near existing substations and population centers, providing the reliability benefits of pumped hydro at locations where hydro is impossible. CEO VanWalleghem has described the company's marginal cost for additional storage hours as roughly $50 per kWh — versus $300+ for lithium-ion — making A-CAES increasingly cost-competitive beyond eight-hour durations.

Hydrostor has raised over C$470 million in total funding from Goldman Sachs Asset Management, the Canada Pension Plan Investment Board (CPP Investments), Canada Growth Fund, Alberta Investment Management Corporation (AIMCo), and the Canada Infrastructure Bank. The company's pipeline spans North America, Australia, and Europe, totaling over 6 GW and 65 GWh in various stages of development.

Hydrostor's first commercial facility — the Goderich Energy Storage Centre in Ontario — has been operating commercially since 2019 under contract with Ontario's grid operator, making it the world's first commercially contracted A-CAES facility. Its flagship projects under advanced development include the 500 MW / 4,000 MWh Willow Rock project in Kern County, California (which received final CEC permitting approval in December 2025 and is targeting shovel-ready status in 2026) and the 200 MW Silver City project in Broken Hill, New South Wales, Australia (which holds a long-term energy services agreement from the NSW Government). Both projects target commercial operation in the 2026–2028 timeframe.